Various environmental and industrial chemicals can disturb male reproductive function. The objective of these studies is to enhance our understanding of this toxic potential, and to elucidate the mechanism of action in chemicals found to be toxic. For FY 86, efforts have focused on in vitro primary cultures of Sertoli cells and their metabolic responses to toxicants whose in vivo spectrum of effects has been fairly well defined: mono-(2-ethylhexyl)-phthalate, 2,5-hexanedione, and acrylamide. Endpoints for this system include glycolytic and overall energy-balance analyses, protein synthesis (both cellular and secreted), and morphology. The emphasis has been on dose- and time-relationships between these endpoints. A method to differentiate peritubular cells from Sertoli cells in vitro was devised and evaluated. These studies are expected to yield information on the response of the Sertoli cell to toxicants which affect it in vivo. A series of studies are ongoing to evaluate the effects of acrylamide and some analogues on the testis of rats. Another set of studies examined the effects of methyl-DOPA on male reproductive function.